Trees, shrubs or climbers, monoecious. Exudate (from cut stems) present, white. Unarmed. Indumentum present, hairs dendritic (multicellular, usually coloured). Stipules free, simple, unlobed, entire, not spine-like*, not leaf-like*, without glands. Leaves distributed evenly along stem, alternate, simple, unlobed, base symmetrical, margin toothed or entire, blade not pellucid-punctate, upper surface without glands, lower surface with (or rarely without) a row of glands more or less near margin, sometimes also minutely papillate or whitish-powdery; venation pinnate or sometimes with 3 veins from base; domatia absent*; stipel-like structures absent. Petioles short, without swellings or bends at base or apex*, without glands. Inflorescence with axis, axillary or terminal, raceme-like, female flowers in basal part, or 0, male flowers in upper part, the male part of the inflorescence often falling away later; bracts of side branches small or leaf-like to varying degrees, glandular or not, floral bracts with or without a pair of elliptic glands, glands sometimes very conspicuous, not leaf-like, green; floral buds initially covered by large bracts; pedicels present, distinct, articulated or not. Male flowers: sepals 4–6, partially fused, greenish; petals 0; disc 0; stamens 3–about 100, filaments almost absent or distinct, free; anther without conspicuous modification, thecae extrorse in bud; pistillode absent. Female flowers: sepals (3–) 6 (–9), partially fused, without glands or with few to many elliptic glands at margins, greenish; petals 0; disc 0; ovary locules 3, ovules per locule 1; styles 3, completely fused into a short or long column (stigmas free)*, stigmas 3, free, entire, not flat*, surface smooth*; staminodes absent. Fruit dehiscent, smooth or horned, densely hairy, greenish to brown; seed with or without small caruncle, with no other covering or membranous layer; embryo flat, not minute, cotyledons leaf-like.
An asterisk * indicates a state has been assumed but not yet confirmed.
World Checklist: about 40 spp.
With thanks to Hans-Joachim Esser (Botanische Staatssammlung München) for help with this genus.